Robert F. Shepherd’s research while affiliated with Cornell University and other places

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Publications (154)


Modular pod for self‐contained actuation in soft robots. A) The pod is an independent modular unit that includes an actuation mechanism and energy entities. The zinc‐iodide redox flow battery, standard voltage of 1.3 V, integrated into each pod self‐powers the entire system. The amount of catholyte filling the pod and the anode area in the inner pouches enable the high capacity of the battery (118 mAh cm⁻², 3387 mWh). B) The actuation mechanism of the pod mimics a hydrostatic skeleton of a worm, creating radial expansion by axial contraction of an incompressible body. A DC motor and a tendon in each pod drive the full contraction (ΔL/L = ≈10%) within 1.8 s, achieving rapid actuation. C) The modularity of the pods enables easy reconfiguration and independent control of contraction and expansion. A series of four connected pods generated various patterns of sequential actuation for effective forward motion, adaptable as needed. Peristaltic locomotion and two‐anchor locomotion were demonstrated on a flat surface and inside a pipe, respectively.
Demonstration and characterization of the pouch anode cell. A) Schematic of the pouch anode cell containing the anode composite within a sealed enclosure made of ion‐exchange membranes. The anode composite consists of a stainless steel mesh (200 wires per inch) sandwiched between two layers of 0.35 mm carbon cloth. An 8 cm² anode was used, matching the size of the anode in the worm robot. The gas vent at the top of the frame improved the cyclic performance by releasing accumulated hydrogen. B) The ion‐exchange membrane, which constitutes the top and bottom faces of the anode pouch, prevents the mixing of catholyte and anolyte while allowing the passage of Zn²⁺ during charge and discharge. During charging, zinc ions from the catholyte migrate into the pouch and deposit as metallic zinc on the anode surface, while oxidized iodide ions form triiodide, giving the solution a deep red color (bottom left and right in inset). C) Polarization curve for the multiple pouches. Multiple pouches share the catholyte and function as a battery connected in parallel. D) Capacity curve for the multiple pouches. Multiple pouches provide the surface area, which is the bottleneck for capacity, thereby enabling greater overall capacity. E) Torque on the motor powered by the multiple pouches. Multiple pouches supplied greater power to the motor, enabling it to generate higher torque.
Mechanism and performance of the dry‐adhesion between Nafion and polyurethane. A) Photograph of the adhesion surface showing cohesive failure on polyurethane substrate, The scale bar is 10 mm. B) Upon contact, the adhesion forms instantly by intramolecular interaction such as hydrogen bond or electrostatic interaction, followed by the urethan linkage attributed to a stable bond. C) Force–displacement curve measured using T‐peel test for the adhesion samples; as‐prepared (black), immersed in D.I. water for 1 d (red), and 10 d (blue). The specimen width was 1 cm, and the crosshead speed of the tensile test was set to 0.05 mm s⁻¹ to minimize viscoelastic effects and localized stress concentrations. D) The duration of surface reactivity in cured polyurethane substrates was tested. Polyurethane substrates were fully cured using a normal curing process, which involved UV 3D printing followed by thermal curing at 120 °C. After curing, the substrates were stored at room temperature for different durations—1 d, 10 d, and 1 year—before bonding tests were conducted. E) Stability of the adhesion over time (1 d, 3 d, and 10 d) after the bonding. Once the bond was formed, no decrease in bonding strength was observed over time. (Error bars indicate SDs, n = 3).
Mechanical and electrochemical characterization of the pod. A) The exploded view of the pod. The pod includes four anode pouches in the center that is surrounded around by the cathode. Inside and outside of the pod was filled with 3 m zinc iodide solution. B) The hydrostatic skeleton inspired actuation module, axial contraction of the pod, driven by a tendon‐motor mechanism, results in radial expansion due to the presence of an incompressible electrolyte. C) Dimension changes and power consumption during actuation. The peak power was 0.59 W at full contraction, while in the passive extension phase, which used stored elastic energy, power consumption dropped to about 0.2 W, the minimum required for control. D) Compressive loading and unloading curves of the pod. The force required for a 6 mm stroke, from 6 mm to 12 mm including preloading, was 19.5 N. The internal battery components, arranged to minimize interference with pod motion, required only an additional 1 N for contraction. E) Polarization curve of the single module integrated with four pouches. Upon completing all integrations, a single pod produced approximately 0.175 W at the target voltage of 0.9 V, and the total power of the robot that consists of four pods was confirmed to exceed 0.7 W. F) Total discharged energy capacity for single actuation module. The single pod with 32 cm² of anode and 60 mL of 3 m ZnI2 catholyte discharged 3387 mWh with 85% of Coulombic efficiency. The inset figure shows a voltage drop when the module was discharged with static mode.
Locomotion performance of the untethered crawling robot. A,B) Demonstration of the robot on a flat surface with a peristaltic locomotion pattern and in the pipeline with a two‐anchor locomotion pattern. R and C in the schematic figure denote the relaxed and contracted state, respectively. The inner diameter of the pipe was 65 mm. C) Trajectory of the worm head during locomotion. Black curve: The stride length and cycle duration for the peristaltic locomotion pattern were 4.7 mm and 9.3 s, achieving a net speed of 30 mm min⁻¹. Red curve: The stride length and cycle duration for the two‐anchor locomotion pattern were 8.2 mm and 11.3 s, achieving a net speed of 44 mm min⁻¹. D) Navigating within the pipeline that has the hexagon‐shaped path combined with straight segments (L: 300 mm) and curved segments (L: 300 mm, R: 300 mm). The overall duration for a single round trip and distance is 1 h 20 min and 3.8 m. The energy used for the trip is estimated to be approximately 500 mWh, which accounts for about 4% of the robot's total energy capacity. E) The robot climbs up and down in the vertical pipe with 25 and 50 mm min⁻¹ speed.
Soft, Modular Power for Composing Robots with Embodied Energy
  • Article
  • Full-text available

January 2025

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29 Reads

Chong‐Chan Kim

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Anunth Rao Ramaswami

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Robert F. Shepherd

The adaptable, modular structure of muscles, combined with their confluent energy storage allows for numerous architectures found in nature: trunks, tongues, and tentacles to name some more complex ones. To provide an artificial analog to this biological soft muscle, a self‐powered, soft hydrostat actuator is presented. As an example of how to use these modules, a worm robot is assembled where the near totality of the body stores electrochemical potential. The robot exhibits an extremely high system energy density (51.3 J g⁻¹), using a redox flow battery motif, with a long theoretical operational range of more than 100 m on a single charge. The innovation lies in the battery pouch, fabricated with a dry‐adhesion method, automatically bonding Nafion separators to a silicone‐urethane copolymer body. These pouches contain anolyte within a hydrostat pod filled with catholyte, increasing current density per pod. Each pod has a motor and tendon actuator for radial compression and expansion. By linking these self‐contained pods in series, the robot worm is created that automatically navigates an enclosed, curved path. This high‐capacity soft worm also climbs up and down a vertical pipe, using a two‐anchor crawling gait, with an extra payload equivalent to 1.5 times its body weight.

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The multifunctional use of an aqueous battery for a high capacity jellyfish robot

November 2024

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63 Reads

Science Advances

Xu Liu

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Shuo Jin

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Yiqi Shao

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[...]

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Robert F Shepherd

The batteries that power untethered underwater vehicles (UUVs) serve a single purpose: to provide energy to electronics and motors; the more energy required, the bigger the robot must be to accommodate space for more energy storage. By choosing batteries composed primarily of liquid media [e.g., redox flow batteries (RFBs)], the increased weight can be better distributed for improved capacity with reduced inertial moment. Here, we formed an RFB into the shape of a jellyfish, using two redox chemistries and architectures: (i) a secondary ZnBr 2 battery and (ii) a hybrid primary/secondary ZnI 2 battery. A UUV was able to be powered solely by RFBs with increased volumetric ( Q ~ 11 ampere-hours per liter) and areal (108 milliampere-hours per square centimeter) energy density, resulting in a long operational lifetime ( T ~ 1.5 hours) for UUVs composed of primarily electrochemically energy-dense liquid (~90% of the robot’s weight).


Figure 1. Architectural complexity levels, C, shown with representative examples. From left to right: C = 0 corresponds to atomic elements (shown: argon), C = 1 corresponds to single materials (shown: a steel bar), C = 2 corresponds to blends and formulations (shown: a colloidal gel), C = 3 corresponds to composite materials (shown: a carbon fiber joint), C = 4 corresponds to 3D metamaterials (shown: a double-gyroid capacitor capable of sensing, energy storage, and load bearing, 60 and C = 5 corresponds to material systems and electromechanical devices with structural hierarchies spanning 6+ orders of magnitude (shown: a microelectronic chip highlighting transistor junctions 11 ).
Figure 2. Different levels of autonomy in vehicles and correlating examples of autonomy in materials systems. Top row: The six levels of autonomous vehicles as defined by The Society of Automotive Engineers. Bottom row: examples of corresponding autonomous material system. From left to right: a rock (A = 0), a piezoelectric bimorph (A = 1), 13 a self-healing polymer (A = 2), 23 Belousov-Zhabotinksy (BZ) hydrogels (A = 3), 17 a paramecium (A = 4), and a Portuguese man o' war (A = 5). 45 For the materials shown, each level of autonomy, A, correlates to the Automated Driving System as follows: A = 0 is inert, A = 1 demonstrates feedforward actuation, A = 2 demonstrates decoupled computation, A = 3 demonstrates collocated capabilities, A = 4 demonstrates groups of collocation, and A = 5 demonstrates tight integration. Green-bordered materials have been achieved in the literature, while red-bordered are biological examples that we display to aid our discussion.
Figure 3. A Pareto front of autonomy (A) versus architectural complexity (C) based on our autonomous material system guidelines. Several examples for this text (ranging from molecular elements to multicellular organisms) are depicted and placed according to their [C, A] values. Examples in red are biological in origin (from bottom to top: mother of pearl, a bacteriophage virus, a neutrophil, a paramecium, a slime mold, and a Portuguese man o' war). Examples in green, with the exception of elemental fluorine, are exemplary of current scientific developments (from left to right: steel alloy bars, elemental fluorine, Belousov-Zhabotinsky gel composites, self-healing materials, the Spot robot by Boston Dynamics (photo credit: D. Newman, D. Colli, and D. Berenson), and a modern electric vehicle.
Figure 4. Autonomy through a hierarchy of collective coordination observed in the Portuguese man o' war (Physalia physalis [P. physalis]) siphonophore. (a) A Portuguese man o' war photographed in the ocean and (b) on the beach. (c) An illustration of the Portuguese man o' war with zooid anatomy labeled. **There is terminological inconsistency within the literature regarding the anatomy of P. physalis, notably with respect to the tentacle-like structures that hang below the pneumatophore. Some researchers collectively refer to these as dactylozooids, whereas others distinguish the tentacle as a separate entity. 45
Autonomous material systems

October 2024

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239 Reads

MRS Bulletin

This article describes the challenges of defining and classifying autonomous material systems. We believe that there is no consistent definition of “autonomy” across different scientific disciplines, and this difference makes it difficult to assess progress as a whole. The authors pose that there is a paradox between achieving greater autonomy and, presently, maintaining an achievable cost of material system complexity. Examples are given from the artificial and biological world and make the, somewhat safe, claim that organisms make a better tradeoff between the manufacturing complexity required to build autonomy. The authors draw from the Autonomous Driving System scale to classify autonomy levels in material systems, and give specific examples of increasing architectural complexity. We then call out specific research trajectories to pursue in order to make better tradeoffs in this engineering contradiction, manufacturing being a specific example. This article will hopefully bring some uniformity between different materials science disciplines. Graphical abstract


Transdisciplinary collaborations for advancing sustainable and resilient agricultural systems

September 2024

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29 Reads

Feeding the growing human population sustainably amidst climate change is one of the most important challenges in the 21st century. Current practices often lead to the overuse of agronomic inputs, such as synthetic fertilizers and water, resulting in environmental contamination and diminishing returns on crop productivity. The complexity of agricultural systems, involving plant-environment interactions and human management, presents significant scientific and technical challenges for developing sustainable practices. Addressing these challenges necessitates transdisciplinary research, involving intense collaboration among fields such as plant science, engineering, computer science, and social sciences. Here, we present five case studies from two research centers demonstrating successful transdisciplinary approaches toward more sustainable water and fertilizer use. These case studies span multiple scales. Starting from whole-plant signaling, we explore how reporter plants can transform our understanding of plant communication and enable efficient application of water and fertilizers. We then show how new fertilizer technologies could increase the availability of phosphorus in the soil. To accelerate advancements in breeding new cultivars, we discuss robotic technologies for high-throughput plant screening in different environments at a population scale. At the ecosystem scale, we investigate phosphorus recovery from aquatic systems and methods to minimize phosphorus leaching. Finally, as agricultural outputs affect all people, we show how to integrate stakeholder perspectives and needs into the research. With these case studies, we hope to encourage the scientific community to adopt transdisciplinary research and promote cross-training among biologists, engineers, and social scientists to drive discovery and innovation in advancing sustainable agricultural systems.


Sensorimotor control of robots mediated by electrophysiological measurements of fungal mycelia

August 2024

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647 Reads

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2 Citations

Science Robotics

Living tissues are still far from being used as practical components in biohybrid robots because of limitations in life span, sensitivity to environmental factors, and stringent culture procedures. Here, we introduce fungal mycelia as an easy-to-use and robust living component in biohybrid robots. We constructed two biohybrid robots that use the electrophysiological activity of living mycelia to control their artificial actuators. The mycelia sense their environment and issue action potential–like spiking voltages as control signals to the motors and valves of the robots that we designed and built. The paper highlights two key innovations: first, a vibration- and electromagnetic interference–shielded mycelium electrical interface that allows for stable, long-term electrophysiological bioelectric recordings during untethered, mobile operation; second, a control architecture for robots inspired by neural central pattern generators, incorporating rhythmic patterns of positive and negative spikes from the living mycelia. We used these signals to control a walking soft robot as well as a wheeled hard one. We also demonstrated the use of mycelia to respond to environmental cues by using ultraviolet light stimulation to augment the robots’ gaits.



Overview and design for overprinting. a) The design progression of the finger showing an x‐ray of the human hand bones (i) and the middle phalange up close (ii). The middle phalange shown with a lattice network (iii) and simple male and female hinge attachments (iv). A 3D model of the whole endoskeletal finger with arrow indicating the middle phalange location (v). The black box in a,i identifies all three phalange bones while the red dashed box identifies the middle phalange that is detailed in a,ii–iv. b) Gelatin Methacrylate monomer backbone with red circles indicating the methacrylate groups that create chemical crosslinks during UV radiation in the presence of a photoinitiator. A schematic of the chemical structure of the crosslinked GelMA surrounding the finger alongside renderings of the actuating finger before (ii,iii) and after (iv,v) swelling. c) Modularly built Computed Axial Lithography Printer with a light engine (i) that projects through a condenser lens (ii) into the vial suspended in a cube of index matching liquid (iii). The vial is attached to a rotation stage on a manual Z‐stage (iv) controlled by the DC motor controller (v). The scale bars represent 1 cm.
Critical dose calculation. a) 3D visualization of the overprinting process where the light is occluded by the insert from two perpendicular projection angles. b) A voxelized vertical slice through the finger (i) showing the insert in red surrounded by the hydrogel in white and the out‐of‐part region in black alongside a normalized dose distribution of the same slice with a color map (ii) generated from OSMO with occlusion. The green dashed line represents the Z‐slice used in c). The axes correspond to the voxel resolution. c) Dose profile progressions (i) from one Z‐slice of the finger during printing showing the cumulative angular contributions from 1, 90, 180, and 270 angles of projections generated from our ray‐based method. Ray‐based absolute dose profiles for one Z‐slice of the finger after one full rotation of 360 projection angles (i) and shown with the insert and out‐of‐part voxels set to zero (ii) for easier visualization. The dose range of the voxels in the hydrogel region of the finger is noted above the image.
GelMA resin formulation testing. a) 10 wt% GelMA disks with 0.05 wt% LAP before (left) and after (right) swelling for 12 h in 90 °C water. b) Comparison of the effect of the GelMA concentration (i) on the swelling for samples at 0.2 wt% LAP and comparison of the effect of the LAP concentration (ii) on the swelling for samples at 10 wt% GelMA. c) Comparison of the effect of post‐curing intensity on the swelling for samples at 10 wt% GelMA and 0.05 wt% LAP. d) Rheology for 10 wt% GelMA resin with 0.05 wt% LAP. A thermal ramp was applied (i) to determine the thermal gelation temperature and a stress amplitude ramp (ii) was applied to determine the yield stress. The vertical line in (i) and (ii) identifies the crossover temperature and the yield stress respectively. Note that the brightness and contrast were adjusted for the inset images in (i) to aid visualization. e) The stages of vial preparation for overprinting. The bones are suspended in the vial center (i) and the vial is partially filled by resin before cooling (ii). The vial is then filled (iii) and cooled again before it is ready to print with. The scale bars represent 1 cm. All error bars represent one standard deviation.
Overprinting and actuation results. a) Live overprinting process showing the light shadow being formed from the front (i) and side (ii) profile of the endoskeleton. The overprinted finger viewed from the side (iii) and the back (iv). b) Overlayed images showing the bending achieved after 7 h in 90 °C DI water (i). The colors of the angles (red [proximal joint], black [distal joint], and blue [total]) correspond to the curves shown in (ii). Timeline of the bending progression over 7 h with overlayed images of the bending progress every hour (ii). The scale bars represent 1 cm.
Volumetric 3D Printing of Endoskeletal Soft Robots

June 2024

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51 Reads

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4 Citations

Computed Axial Lithography (CAL) is an emerging technology for manufacturing complex parts, all at once, by circumventing the traditional layered approach using tomography. Overprinting, a unique additive manufacturing capability of CAL, allows for a 3D geometry to be formed around a prepositioned insert where the occlusion of light is compensated for by the other angular projections. This method opens the door for novel applications within additive manufacturing for multi‐material systems such as endoskeletal robots. Herein, this work presents one such application with a simple Gelatin Methacrylate (GelMA)hydrogel osmotic actuator with an embedded endoskeletal system. GelMA is an ideal material for this application as it is swellable and has reversible thermal gelation, enabling suspension of the endoskeleton during printing. By tuning the material formulation, the actuator design, and post‐processing, swelling‐induced bending actuation of 60 degrees is achieved. To aid in the printing process, a simple computational method for determining the absolute dose absorbed by the resin allowing for print time prediction is also proposed.


Waterbomb origami antenna design and working principle. A) Ring antenna and motor–tendon‐driven (WRAP) actuator design and working; B) WRAP integrated with an eight‐patch assembled ring antenna in a flat state and its radiation pattern; and C) antenna in a folded state and its radiation pattern.
Hinge design, assembly, and two‐patch Antennas. A) Hinge design schematic. B) A cartoon depiction showing LM contact in the hinge, joining with two patches. C) Two‐patch antenna for EM performance evaluation. D) LM‐filled hinge cross‐sectional view from a micro‐CT scan, showing LM distribution in flat and folded states. E) Resistance changes under hinge folding up to 90°. F) Reflection coefficient (S11) simulation and experimental measurements at various folding angles of the two‐piece patch antenna.
WRAP System. A) Waterbomb antenna folding images set with FAR and FA measurements. B) Antenna folding angle versus tendon displacement. C) Antenna pulling force versus tendon displacement. D) Measurements of antenna folding angle versus pulling force. E) Folding angle correlation with motor rotation. F) WRAP integration on wheelbot.
Waterbomb antenna EM analysis in flat and folded modes. A) Assembled waterbomb antenna. B,C) Simulated surface current distribution | Jsurf |$\left|\right. J_{\text{surf}} \left|\right.$ in mode 1 and mode 2. D,E) Simulated and measured reflection coefficient, and peak polarized gain for mode 1 and mode 2 in the flat state. F,G) Experimental mode 1, x^$\overset{\Hat}{x}$/y^$\overset{\Hat}{y}$ polarized 3D gain pattern simulated at 2.08 GHz, flat state. H,I) Experimental mode 2, x^$\overset{\Hat}{x}$/y^$\overset{\Hat}{y}$ polarized 3D gain pattern at 2.43 GHz. J,K) Simulated and measured reflection coefficient, and peak polarized gain for mode 1 and mode 2 in the folded state. L,M) Experimental mode 1, x^$\overset{\Hat}{x}$/y^$\overset{\Hat}{y}$ polarized 3D gain pattern at 2.08 GHz, folded state. N,O) Experimental mode 2, x^$\overset{\Hat}{x}$/y^$\overset{\Hat}{y}$ polarized 3D gain pattern at 2.43 GHz, folded state.
Waterbomb antenna communication and robot demonstration. A) Communication between two robots. B) Transmitted spectrum. C) Received spectrum. D) Schematic of Simulink implementation of transmitter and receiver. E) MER measurement in both modes for flat and bend state antenna. F) Waterbomb antenna with wheelbot demonstrating navigation through a narrow pass. G) Waterbomb antenna folding posture while passing through a narrow pass.
Robotic Antennas Using Liquid Metal Origami

June 2024

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175 Reads

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1 Citation

Two of the main challenges in origami antenna designs are creating a reliable hinge and achieving precise actuation for optimal electromagnetic (EM) performance. Herein, a waterbomb origami ring antenna is introduced, integrating the waterbomb origami principle, 3D‐printed liquid metal (LM) hinges, and robotic shape morphing. The approach, combining 3D printing, robotic actuation, and innovative antenna design, enables various origami folding patterns, enhancing both portability and EM performance. This antenna's functionality has been successfully demonstrated, displaying its communication capabilities with another antenna and its ability to navigate narrow spaces on a remote‐controlled wheel robot. The 3D‐printed LM hinge exhibits low DC resistance (200 ± 1.6 mΩ) at both flat and folded state, and, with robotic control, the antenna achieves less than 1° folding angle accuracy and a 66% folding area ratio. The antenna operates in two modes at 2.08 and 2.4 GHz, ideal for fixed mobile use and radiolocation. Through extensive simulations and experiments, the antenna is evaluated in both flat and folded states, focusing on resonant frequency, gain patterns, and hinge connectivity. The findings confirm that the waterbomb origami ring antenna consistently maintains EM performance during folding and unfolding, with stable resonant frequencies and gain patterns, proving the antenna's reliability and adaptability for use in portable and mobile devices.



Powerful, soft combustion actuators for insect-scale robots

September 2023

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119 Reads

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39 Citations

Science

Insects perform feats of strength and endurance that belie their small stature. Insect-scale robots—although subject to the same scaling laws—demonstrate reduced performance because existing microactuator technologies are driven by low–energy density power sources and produce small forces and/or displacements. The use of high–energy density chemical fuels to power small, soft actuators represents a possible solution. We demonstrate a 325-milligram soft combustion microactuator that can achieve displacements of 140%, operate at frequencies >100 hertz, and generate forces >9.5 newtons. With these actuators, we powered an insect-scale quadrupedal robot, which demonstrated a variety of gait patterns, directional control, and a payload capacity 22 times its body weight. These features enabled locomotion through uneven terrain and over obstacles.


Citations (80)


... Fungal mycelium has been shown to increase conductivity and communication speed when stimulated at two separate points, which allows for the establishment of memory, akin to how brain cells form habits. Different geometries of mycelium can compute various logical functions, which can be mapped based on its electrical responses (Phillips et al. 2024). Nowadays, taking advantage of fungal mycelia's natural light sensitivity, Mishra et al. (2024) developed an electrical interface to both house the mycelia and measure their electrophysiological action potentials. The following are potential applications: ...

Reference:

REVIEW Open Access Review on mushroom mycelium-based products and their production process: from upstream to downstream
Sensorimotor control of robots mediated by electrophysiological measurements of fungal mycelia
  • Citing Article
  • August 2024

Science Robotics

... In conclusion, we systematically demonstrate the possible impacts of particle-wall alignment interactions on unbiased transport through narrow channels. Our findings, which are summarized above, would help us better understand the transport control mechanism of active particles through narrow structures aiming at targeted drug delivery and other cutting-edge nanotechnological applications [81][82][83] . Further, our study brings up several related issues for future work. ...

Introduction to Soft Robotics
  • Citing Article
  • June 2024

Soft Matter

... GelMA, a highly versatile biomaterial, is derived from the chemical modification of gelatin via the introduction of methacrylate groups onto the reactive amine and hydroxyl functional groups present on the side chains of its constituent amino acids, utilizing methacrylic anhydride as the crosslinking agent. This synthetic procedure confers upon GelMA enhanced mechanical properties and biocompatibility, positioning it as a prominent material in various biomedical applications, including cell culture, bio-3D printing, and tissue engineering [39].NMR spectroscopic analysis of both gelatin and its derivative GelMA was conducted to characterize the chemical modifications. The spectra exhibited distinct features, with the appearance of new peaks at 5.45 and 5.69 ppm, which correspond to the vinyl protons of the methacrylate groups. ...

Volumetric 3D Printing of Endoskeletal Soft Robots

... As aforementioned, Al Jamal et al. [274] present the first additively manufactured mm-wave hinge interconnect with an "arch" topology that exhibits nearconstant IL of 0.02 dB/mm across various folding angles and cycles at 28 GHz. Other foldable interconnects at lower frequency bands include liquid metal hinges for a 2.4-GHz origami-inspired antenna [275] and a PCB-milled surrogate hinge structure for a 2.45-GHz antenna array [276]. Any instability in electrical performance due to folding should be either mitigated or intentionally leveraged to introduce controllable frequency and/or pattern reconfigurability. ...

Robotic Antennas Using Liquid Metal Origami

... a Overview of the high frequency, cascade ability, and phase tunable pneumatic hybrid oscillator (PHO) for various robot actuations. b Comparison of the motion speed and frequency of the bionic kangaroo robot designed based on the proposed PHO with the same type of pneumatic robot in the literatures9,14,22,[24][25][26]29,30,[41][42][43][44][45][46][47][48][49][50][51][52] . c The design of PHO. ...

Powerful, soft combustion actuators for insect-scale robots
  • Citing Article
  • September 2023

Science

... Architectural complexity levels, C, shown with representative examples. From left to right: C = 0 corresponds to atomic elements (shown: argon), C = 1 corresponds to single materials (shown: a steel bar), C = 2 corresponds to blends and formulations (shown: a colloidal gel), C = 3 corresponds to composite materials (shown: a carbon fiber joint), C = 4 corresponds to 3D metamaterials (shown: a double-gyroid capacitor capable of sensing, energy storage, and load bearing,60 and C = 5 corresponds to material systems and electromechanical devices with structural hierarchies spanning 6+ orders of magnitude (shown: a microelectronic chip highlighting transistor junctions 11 ). ...

Mechanical Properties of Highly Deformable Elastomeric Gyroids for Multifunctional Capacitors

... An increase in pressure between the electrode and the skin results in changes in contact area and distance, leading to heightened current flow even with the same applied voltage. As a result, even the same stimulation bias can yield different tactile sensations due to variations 24 in touch pressure each time [25][26][27][28] . ...

Harnessing Nonuniform Pressure Distributions in Soft Robotic Actuators

... Active control of metamaterials can be achieved by a variety of methods, such as electromagnetic or pneumatic actuation [14]. Possible applications of pneumatic actuation are wide-ranging from changes in electromagnetic properties of sandwiched material designs [15,16] to soft robots capable of walking motion [17]. For pattern-forming metamaterials, pneumatic actuation has been studied by Chen et al. [18] to describe the relationship between the actuation and the patterning behavior. ...

Harnessing Nonuniform Pressure Distributions in Soft Robotic Actuators

... The possibilities can indeed be extended further by employing a lattice structure instead of a 2.5D supportive structure, which can be specifically designed to bend in a desired manner [19,119] as shown in Figure 2.12. This lattice structure can be highly optimised to achieve various transformations, such as changes in camber, twist, or even span when actuated. ...

Autonomous material composite morphing wing
  • Citing Article
  • January 2023

... The principal properties that identify self-healing behavior in materials are: autonomous healing, recovery of mechanical properties, durability of the healed region, repeatability of healing, efficiency of the healing process, and environmental compatibility. Autonomous healing refers to the material's ability to initiate and complete the healing process without external intervention, including automatic damage detection and the release of healing agents (Hobbs, et al. [19,20]). Recovery of mechanical properties means the material regains its original or near-original mechanical properties, such as strength, stiffness, toughness, and other relevant properties, after healing (Ganesan [21]). ...

Autonomous self-healing optical sensors for damage intelligent soft-bodied systems

Science Advances